Automatic sharpening device for lawnmowers



A ril 6, 1937. v w. B. WHITE 2,076,311

AUTOMATIC SHARPENING DEVICE FOR LAWN MOWERS Filed July 11, 1935 PatentedApr. 6, 1937 PATENT OFFICE AUTOMATIC SHARPENING DEVICE FOR LAWNMOWERSWarren B. White, North Abington, Mass.

Application July 11, 1935, Serial No. 30,864

1 Claim.

My present invention is a novel and improved sharpening instrumentalityfor automatically sharpening the rotating blades of lawnmowers,

or the like.

The object of this invention is to improve and perfect devices of thiskind, particularly as shown in my prior U. S. Letters Patent No.1,945,582, dated February 6, 1934, and my prior pending application Ser.No. 20,590.

As shown in my said prior inventions, I have devised a self-sharpeninglawnmower and abrasive means therefor to cooperate with the rotatingaction of. the spiral cutters toefiect a sharpening of the cuttersduring use. In my said 5 prior devices I utilize means as a part of orad- J'acent to the fixed shearing blade to carry an abrasive surface,but in my present application I have improved the abrasive-carryingmeans and also provide mechanism which will permit the ready removal,replacement, and renewal of abrasive material as the sharpening element.

Furthermore, I have provided in my present improved construction meansto carry the renewable and replaceable abrading element, such as emerypaper, sandpaper, or the like in a constantly yielding tension towardthe rotary cutting blades, which tension may be still further adjustedto any desired degree.

An important feature and advantage of my present improvement is that theself-sharpening element may be varied from a coarse or rough sharpeningaction to a fine or finishing sharpening action, depending upon thegrade of emery paper, or the like, employed and readily interchangeableby the mere slipping off and on of the emery paper.

A further important feature is that my present improvement enables me tosupply a considerable quantity of emery paper, or the like, and

in varying degrees of coarseness and fineness, if desired, in tubularform to readily slip on the holder, and the same will be held in placein any desired or convenient manner.

Preferably, I employ spring-acting means which will hold the emery paperwhen supplied to a supporting element under a yielding tension, andwhich may still further be utilized as yielding tension to hold theentire sharpening element into contact with the rotary blades.

5 Further details, important advantages, and novel combinations will behereinafter more fully pointed out and claimed.

Referring to the drawing illustrating a preferred embodiment of thepresent invention,

Fig. 1 is a vertical View partly in cross-section illustrating theapplication of my present invention to a conventional type of lawnmower;

Fig. 2 is a plan view partly in cross-section and partly broken awayillustrating the sharpening element; and

Fig. 3 is a view in perspective of the sharpening element and holder.

I have illustrated in the drawing a typical or standard type ofhand-operated lawnmower, although it will be appreciated that myinvention is equally applicable to power-driven or horse drawnlawnmowers and of any size, capacity, or style so long as rotary bladesare utilized.

As shown in the drawing, the bracket l extends to the usual push bar ofthe machine, being pivoted at 2 to the framework 3, one of the wheels 4being shown, which rotates and drives through suitable gears (not shown)the axle 5 on which the rotary cutters 6, 6, 6 are mounted on spokes l,l, and which cutters are preferably of. spiral contour operating againsta fixed shearing blade 10. The rear supporting roller 12 is illustrated,as usual, extending across the width of the machine and adjustablymounted in sliding brackets I4 secured to the rear extensions l5 of theframework 3. The fixed cutting bar I0 is pivotally secured to the rearextensions l5 by pivot I6-|6, see Fig. 2, and is adjustable on saidpivots by pairs of thrusting screws ll-ll and 18-48 threaded throughtubed recesses in an extending lug 20 on the extensions l5, also of theusual construction.

Secured to the fixed cutting blade I0 is a rearward brace 24 on which myimproved sharpening holder and abrasive element rest, as shown in Figs.1 and 2. This holder as herein illustrated comprises a metallic V-shapedmember comprising arms 25 and 26, meeting in a V or angle portion 21and, preferably, stamped out of a sheet of metal and preferably, also,of spring metal.

However, such holder may be formed of rubber, fibre, wood, or anysuitable and desired composition. I form the abrasive material 30 in theshape of a tube or sleeve adapted to slide over the holder illustratedin the drawing consisting of the spring arms 25 and 26, which naturallyspread and thus retain the tubular abrasive 30 under tension. As afurther means of holding the abrasive 30 under smooth tension on thearms 25 and 26, I provide a locking rod 33 adapted to engage theabrasive tube or sleeve 30 between the open ends of the V formed by thearms 25 and 26, preferably depressing the tubular portion therebetween,as shown in the drawing and thus retaining the same in assembled andyielding position.

Furthermore, I prefer to utilize the locking arm 33 to hold or press theentire sharpening element into yielding contact with the surfaces of therotary cutters 6, these cutters being spiral, serving to engage theouter surface of the material and tend to force the same rearwardly ofthe machine or against the locking bar 33. To retain the locking bar 33in yielding position and also to hold the entire element in yieldingengagement with the cutter 6, I provide a pair of rods and 36, which areadapted to pass through the eyes or loops 34 at each end of the lockingbar 33, as clearly shown in Figs. 2 and 3.

One end of these rods 35 and 36 is hooked at 38 to engage in recesses inany fixed part of the machine, such as the lug 20, and with the oppositeend portion threaded to receive adjusting nuts 40 which bear upon acoiled spring 44-44 encircling the rods 35 and 36 respectively, andbearing between the locking nuts 40 on each rod and the loop 34 of thelocking bar 33.

This construction permits a quick attachment and detachment of the rods35 and 36, releasing the abrasive tube or sleeve 30 from the holder,permitting quick renewal of a new abrasive tube and replacement of theentire self-sharpening element on the machine.

By my novel tube or sleeve adapted to fit over the holding element, Ihave provided an automatically adjustable yielding and renewableself-sharpening feature for lawnmowers or the like, and I wish to claimthe same herein broadly, and also the tubular abrasive element.

I claim:

A sharpening attachment for the rotary cutter blades of lawnmowers,comprising a V- shaped resilient member of substantially the same lengthas that of the rotary cutter blades to be sharpened, a tubular sheet ofabrasive material adapted to be loosely fitted over said V member, across-bar engaging the abrasive material at the open portion of theV-member holding said abrasive under yielding tension on said member,and yielding means operable on said cross-bar to hold the abrasivematerial in position and to press the same yieldingly toward the rotaryblades to efiect a sharpening action.

WARREN B. WHITE.

